- The volume of a solid can be calculated from its dimensions, if it is a regular shape and is free of air space. How can the volume of an irregularly shaped solid be determined?(Assume the density of the solid is not known.)
Determining the volume of liquids is easy, but solids can be tricky. If the object is a regular solid, like a cube or a sphere, you can measure its dimensions and calculate the volume from its dimensions.
If the object is an irregular solid, like a rock, determining the volume is more difficult. With irregular solids, you can measure the volume by using the Archimedes’ Principle, and finding a suitable liquid in which the body sinks completely.
Suppose you want to measure the volume of a small rock in order to determine its density. Rock sinks completely in water. Therefore, your steps should be as follows:
1. Put some water into a graduated cylinder with markings for every ml., so that there remains sufficient empty space inside the graduated cylinder. Take the initial reading of the volume. Say this is `V_1` .
2. Put the rock in the cylinder cautiously, such that no water is splurged, making sure that it’s totally submerged, and also see that no air is trapped in the surface of the rock. Now read the volume again. Say this reading is `V_2` .
3. The difference in volume, i.e. `(V_2-V_1)` is the volume of the rock in ml.
I like to add some additional data to the answer. If the solid cannot not fully submerged in water we can attach it to a object that can fully submerged in water which has a known volume. Then you can follow the same procedure as the above answer and reduce known volume from the final answer to get the volume of the irregular shape.